PHYLUM CHAROPHYTA

• group of green algae that had characters in common with the land plants

• Phragmoplast

• Cell plate

Phylum Charophyta

Describe the sexual reproduction of phylum charophyta

Do not involve flagellated gametes except in the stoneworts (Charales) where flagellated sperm cells are found

• multicellular

• Superficially resemble land plants because of stem-like and leaf-like structures

• With nodes and internodes

• Typically anchored to the substrate by means of branching underground rhizoids

• Rough to the touch because of deposited calcium salts on the cell wall

Chara (muskgrass/stoneworts)

Describe the asexual reproduction of chara

Takes place by tubers, and secondary protonema

Describe the sexual reproduction of chara

• globule or antheridium (male) producing biflagellate antherozoids

• Nucule or archegonium (female) with oogonium

• filamentous or unicellular

• Reproduction involving conjugation between 2 cells

• No flagellated stages

• All freshwater

Class Zygnematophyceae

• variously shaped unicellular

• Usually 2 chloroplasts with nucleus sited between them

• Often with a narrow isthmus

• Mobility by mucilage secretion

• “Desmids”

Order Cosmariales

What are the representative species of order cosmariales?

• Micrasterias furcata

• Closterium

• Cosmarium sp.

Micrasterias furcata

Closterium

• unbranched, filamentous

• Varied forms of chloroplasts

• Cell wall usually slimy

• Conjugation results in resistant zygospore

Order Zygnematales

What are the representative species of order zygnematales

• Zygnema

• Spirogyra

Zygnema

• freshwater filamentous, free-floating or anchored with a holdfast

• Composed of elongate barrel- shaped cells

• Each with two star-shaped chloroplasts arrayed one after the other along the axis of the cell

Zygnema

Spirogyra

• unbranched with cells connected end to end in long green filaments

• With spiral arranged chloroplasts

Spirogyra

What is the outer wall of Spirogyra made of?

Pectin

What is the inner cell wall of Spirogyra made of?

Cellulose

In Spirogyra what are the centers for starch production?

Pyrenoids

Describe the asexual reproduction of Spirogyra

Fragmentation and mitosis to form new filaments

Describe the sexual reproduction of Spirogyra

Conjugation and formation of zygospore

What are the 2 forms of conjugation in Spirogyra

• Scalariform conjugation= occurs between two filaments

• Lateral conjugation= occurs between two adjacent cells on the same filament